[openstack-dev] [Nova] FFE Request: Ephemeral RBD image support

Josh Durgin josh.durgin at inktank.com
Thu Mar 13 20:36:18 UTC 2014

On 03/13/2014 12:48 PM, Russell Bryant wrote:
> On 03/13/2014 03:04 PM, Josh Durgin wrote:
>> These reverts are still confusing me. The use of glance's v2 api
>> is very limited and easy to protect from errors.
>> These patches use the v2 glance api for exactly one call - to get
>> image locations. This has been available and used by other
>> features in nova and cinder since 2012.
>> Jay's patch fixed the one issue that was found, and added tests for
>> several other cases. No other calls to glance v2 are used. The method
>> Jay fixed is the only one that accesses the response from glanceclient.
>> Furthermore, it's trivial to guard against more incompatibilities and
>> fall back to downloading normally if any errors occur. This already
>> happens if glance does not expose image locations.
> There was some use of the v2 API, but not by default.  These patches
> changed that, and it was broken.  We went from not requiring the v2 API
> to requiring it, without a complete view for what that means, including
> a severe lack of testing of that API.

That's my point - these patches did not need to require the v2 API. They
could easily try it and fall back, or detect when only the default
handler was enabled and not even try the v2 API in that case.

There is no hard requirement on the v2 API.

> I think it's the right call to block any non-optional use of the API
> until it's properly tested, and ideally, supported more generally in nova.
>> Can we consider adding this safety valve and un-reverting these patches?
> No.  We're already well into the freeze and we can't afford risk or
> distraction.  The time it took to deal with and discuss the issue this
> caused is exactly why we're hesitant to approve FFEs at all.  It's a
> distraction during critical time as we work toward the RC.

FWIW the patch that caused the issue was merged before FF.

> The focus right now has to be on high/critical priority bugs and
> roegressions.  We can revisit this properly in Juno.



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